(a) Field of the Invention
The present invention relates to a touch sensitive display device, a driving apparatus thereof, and a method of detecting a touch.
(b) Description of Related Art
A liquid crystal display (LCD) includes a pair of panels provided with pixel electrodes and a common electrode, and a liquid crystal layer with dielectric anisotropy interposed between the panels. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs) such that they receive image data voltages row by row. The common electrode covers the entire surface of one of the two panels and it is supplied with a common voltage. A pixel electrode and corresponding portions of the common electrode, and corresponding portions of the liquid crystal layer, form a liquid crystal capacitor that as along with a switching element connected thereto is a basic element of a pixel. An LCD generates electric fields by applying voltages to pixel electrodes and a common electrode and varies the strength of the electric fields to adjust the transmittance of light passing through a liquid crystal layer, thereby displaying images.
A touch screen panel is an apparatus on which a finger or a stylus is touched to write characters, to draw pictures, or to instruct a device such as a computer to execute instructions by using icons. The touch screen panel has its own mechanism to determine whether and where a touch occurs, and it is usually attached on a display device such as an LCD. However, an LCD provided with a touch screen panel has a high manufacturing cost due to the cost of the touch screen panel, low productivity due to a step for attaching the touch screen panel to the LCD, reduction of luminance of the LCD, increase of the thickness of the LCD, etc. Sensors have been developed that include TFTs, and they are incorporated into pixels in an LCD instead of a touch screen panel. A sensor senses a variation of light incident on a panel or pressure put on a panel caused by a user's finger, etc., to inform the LCD whether the user's finger, etc., touches the screen and where the touch is exerted. However, as the sensors are incorporated into the LCD, signals of the sensor may be affected by driving signals of the LCD. Also, the signals of the sensors may be non-uniform due to degradation of the sensors themselves as well as sensing conditions.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.